ACE Weekly 04/24/2012 - 04/30/2012 All ACE spacecraft subsystems are performing as expected. ======================================================================== Orbit/Attitude: No maneuvers were completed this week. The next attitude maneuver is scheduled for Friday 05/04/2012. For the 5/4/2012 maneuver, the spacecraft attitude will have the sun angle dropping to 3 degrees over the subsequent week. There will be no impact to the sun pulse generation (nutation will be zero). The sun angle during the February 2012 sun crossing had gone down to 1.45 degrees and the sun pulse generation was not impacted. Since this week's Solar Exclusion Zone transit is farther from the sun (0.68 degrees versus crossing the sun), a 3 degree sun angle is best for optimizing the High-Gain Antenna pointing towards Earth. ======================================================================= OCRs: MOCR 428 has been submitted for Mission Director approval for the sun angle to go below 4 degrees from Tuesday 5/8/2012 1900z to Sunday 5/13/2012 2300z. The minimum sun angle will be 3 degrees. ======================================================================== Activities: Data Capture: 100% DOY 113-120 2012 The next Solar Exclusion Zone transit (SEZ) is next week with a minimum Sun-Earth-Vehicle angle (SEV) of 0.67 degrees on Sunday 5/6/2012. No problems are expected with current solar radio flux levels (<150 sfu). WS1 ranging test on Monday 04/30/2012. WS1 found that their ranging software was storing values with 32 bits, which was insufficient to store the larger values associated with L1 (ACE/L1 ~1,500,000km; LRO/moon ~385,000km). WS1 has upgraded their software (dll's) and testing continues. ======================================================================== Anomalies: DOY 119 04/28/2012 S-ACE-0641 G12-0004 DSN Replacement Router and SLE The MMOC SLE connection was successfully established at 20 minutes before BOT (2020z). DSN installed a replacement router (2032z) and the MMOC SLE connection was lost. The MMOC SLE telemetry processes (RT+PB) subsequently crashed. The DSN replacement router was taken offline and the ACE pass procedure was restarted from scratch (2106z). IMPACT: Activities delayed 30 minutes. FOT needed to come in for manual intervention (Saturday). Update on AR#S12-0001 S-ACE-0639 SWEPAM-E Overcount Alarm The SWEPAM-Electron Overcount Alarm stopped flagging on DOY 117 07:48:38z. The instrument team is working the next course of action, but their time is limited. IMPACT: The instrument automatically reduces voltages when the overcount alarm occurs.